Reference for Kiddushin 1:10
כָּל הָעוֹשֶׂה מִצְוָה אַחַת, מְטִיבִין לוֹ וּמַאֲרִיכִין לוֹ יָמָיו וְנוֹחֵל אֶת הָאָרֶץ. וְכָל שֶׁאֵינוֹ עוֹשֶׂה מִצְוָה אַחַת, אֵין מְטִיבִין לוֹ וְאֵין מַאֲרִיכִין לוֹ יָמָיו וְאֵינוֹ נוֹחֵל אֶת הָאָרֶץ. כָּל שֶׁיֶּשְׁנוֹ בַמִּקְרָא וּבַמִּשְׁנָה וּבְדֶרֶךְ אֶרֶץ, לֹא בִמְהֵרָה הוּא חוֹטֵא, שֶׁנֶּאֱמַר (קהלת ד) וְהַחוּט הַמְשֻׁלָּשׁ לֹא בִמְהֵרָה יִנָּתֵק. וְכָל שֶׁאֵינוֹ לֹא בַמִּקְרָא וְלֹא בַמִּשְׁנָה וְלֹא בְדֶרֶךְ אֶרֶץ, אֵינוֹ מִן הַיִּשּׁוּב:
Whoever does one mitzvah [above and beyond his merits, so that his merits are more than his transgressions] is benefited, and his days are lengthened [in the world to come], and he inherits the land ["the land of life"]. And whoever does not do one mitzvah [If his transgressions are more than his merits, and he does not do one mitzvah to make himself half innocent-half guilty, but his transgressions remain more], he is not benefited, his days are not lengthened, and he does not inherit the land. Whoever devotes himself to Scripture, Mishnah, and proper conduct (derech eretz) will not quickly sin, viz. (Koheleth 4:12): "And whoever does not devote himself to Scripture, Mishnah, and derech eretz, [i.e., one who does not deal honestly with others] is "beyond the pale" [i.e., he does not contribute to the advancement of the world, his seat is a "seat of scoffers," and he is unfit to testify.]